This particular one was at about 1.5m/5ft. I have taken the same shot at longer focal lengths and correspondingly longer distances, up to 5m/15ft. All focal lengths show the same problem.

This was shot at home (with the resolution chart taped to the refrigerator) so it's obviously not perfect, but I did strive to align it the best I could. I estimate a possible misalignment of the chart at maybe +-2mm/0.1" to the front or to the back. At 75mm and wide open, the DOF calculators give me 4cm/1.5", so that should've been good enough I guess.

No, I did not try to focus on the corners. If I understand it correctly, the reviewers take measurements based on flat targets, so if they got a good result that way, I figure I should be able to do the same.